Many new and existing golf courses have narrowed their fairways and expanded their rough areas on either side of the fairways. Roughs require less care than fairways, so narrowing the fairways allows golf course operators to lower their maintenance costs. For example, irrigation requirements may be reduced if only the fairways are watered. If grasses in the roughs are allowed to grow longer, those non-irrigated areas are less brown. Trees and other aesthetic features may be located in the roughs, because roots and shade can inhibit turf growth in the fairways.
However, golf course roughs still must be maintained regularly using grass mowing machines that can mow the vegetation at an acceptable length and appearance. Equipment for mowing golf course roughs typically includes a traction vehicle carrying three or five rotary cutting decks, each rotary cutting deck mounted on the end of a lift arm extending from the traction vehicle. Each rotary cutting deck may have a hydraulic direct driven spindle that fastens a rotary cutting blade to a hydraulic motor. Conventional rotary cutting decks with hydraulic direct driven spindles capture a central part of the blade in a slot at the lower end of the spindle.
A first problem with conventional rotary cutting decks having hydraulic direct driven spindles occurs if the captured blade starts to become loose. If this occurs, the blade will continue to be driven by the hydraulic motor and will maintain momentum until it detaches completely. This presents a risk to operators and bystanders. A rotary cutting deck with a hydraulic direct driven spindle is needed that reduces the likelihood of driving the blade at high rotational speeds if it starts to become loose, and reduces the risk of blade detachment at high rotational speeds.
A second problem with conventional rotary cutting decks having hydraulic direct driven spindles occurs if the blade strikes a stationary object such as a large rock or stump. If this occurs, the blade, spindle or hydraulic motor may become damaged or fracture from direct axial loads. Unlike rotary cutting decks with belt drives that allow the spindle and blade to slip, decks with hydraulic direct driven spindles have captured blades that cannot slip. There is a need for a rotary cutting deck with a hydraulic direct driven spindle that can reduce the risk of damage or fracture of the blade, spindle or hydraulic motor if the blade strikes a stationary object.